As electron beam apparatuses for inspecting patterns on a substrate for defects and the like for evaluation, there are known a scanning electronic microscope (SEM) and a transmission electronic microscope (TEM) which have ultra-high resolutions using axial chromatic aberration correcting lenses. An electron beam apparatus using an axial chromatic aberration correcting lenses is disclosed in Lecture Preliminary Report of 52-th Applied Physics United Meeting (Spring 2005 in Saitama University), p 812 and p 815. Conventional axial chromatic aberration correcting lenses and spherical aberration correcting lenses have four or twelve electrodes or magnetic poles.
Conventionally, such axial chromatic aberration correcting lenses and spherical aberration correcting lenses have been used to simply reduce the resolution. However, when semiconductor devices are manufactured and/or evaluated using an electron beam apparatus, the processing speed should sometimes be largely increased, inferior to a critical resolution such that the resolution is kept unchanged at several tens of nm. However, since an axial chromatic aberration correcting lens or a spherical aberration correcting lens used in an electron beam apparatus increases a light path length, a space charge effect is increased, which may cause the processing speed increased. Particularly, in the current situation where samples are made increasingly more dense and patterns on the samples are increasingly miniaturized, it is important to solve the problem of space charge and evaluate the patterns at a high throughput. Conventional electron beam apparatuses, however, are incapable of solving such a problem of space charge effect.
Also, conventional multi-pole aberration correcting lenses can cause additional aberration depending on the field of fringes. Moreover, no prior art has been found, which uses an NA aperture member having a large opening, and is capable of increasing a beam current, or reducing the space charge effect, by correcting aberration such as axial chromatic aberration and spherical aberration.
Further, while an electron beam apparatus comprises a beam separator, a place at which the beam separator should be installed is limited to a position conjugate with a sample surface, in order to avoid deflection aberration caused by the beam separator. This leads to such problems as difficulties in down-sizing the electron beam apparatus due to a longer light path length of the apparatus, blurred images resulting from deflection aberration caused by the beam separator, and the like.
Further more, there has conventionally been known an electron beam apparatus which forms a plurality of beams to scan a sample, and detects secondary electron beams emitted from the sample by a plurality of detectors such that a sample image can be captured. However, such an electron beam apparatus has problems of the inability to generate a large beam current and an extremely small throughput, due to aberration, if the resolution is reduced.
In addition, some of conventional electron beam apparatuses employ a high luminance electron gun, reduce a beam into a smaller diameter with a small angular aperture for scanning on a substrate, and capture images. Since such electron beam apparatuses has a small angular aperture and a consequently deep focus depth, the image quality does not exacerbate even if the height of a wafer surface varies in a range of several μm to several tens of μm. However, when patterns on a sample are miniaturized, if axial chromatic aberration is corrected for operation with a large aperture in order to achieve a high throughput, a problem arises in that a large focus depth cannot be provided.